I never claimed that all religions are the same, not even that there are differences in spectrums I pointed out. I only contradicted your claims of fundamental differences.

Be specific: what do you consider an "extreme example" or a "superficial similarity" and why?

I don't get what "political demand" changes about the fact that the Church of England unites political and religious leadership just like the caliphate doctrine. Meanwhile, I don't view the caliphate doctrine as it developed as purely rooted in religion, either. Soon after Mohammed, it was transformed into a quite political justification for the hereditary imperial power of a clan (contrary to original Islamic notions of choosing a leader), and even later the Ottoman sultans claimed the title for their own imperial benefit (legitimising rule over Arabs) despite lack of descent from Mohammed. This, I note, wasn't too successful in practice when a string of Arab kingdoms defied central rule and gained semi-independence.

What is the narrative you are constructing with this "orthodox backlash"? Are you, like the author in the Atlantic, ignoring all other factors affecting various parts of the Arab world (European colonialists, CIA coups, Israel, etc...) and claim an intrinsic development? If we just speak about Iran, it has a very interesting history which doesn't lend itself to such simple narratives. For example, 47 years before the CIA-funded coup d'état against secular leftist PM Mohammad Mosaddegh, there was the Persian Constitutional Revolution, in which a broad coalition including clerics, merchants and advocates of Western-style reforms, united in rejection of submission to European colonialists, forced the Shah to establish a parliament. Those aren't the fault lines of The Atlantic's narrative. In fact, the fault lines in the 1979 Revolution weren't quite like that, either: in both Iran and the West, the fact that the revolution was the work of a broad coalition from Khomeini to communists was airbrushed from history (after establishing power, Khomeini quickly went after his former allies).

Furthermore, it is totally off to claim a switch from relaxed times to orthodox backlash for the entire Islamic world on the example of Iran. There was a more or less synchronous development in urban Afghanistan, Egypt and Palestine, but elsewhere, I don't think so. If anything, the Gulf States minus Saudi Arabia became more relaxed over the same time period, while orthodox madness started in Pakistan with independence. And as bad as Erdoğan is, IMHO it is a stretch to call developments in Turkey an orthodox backlash: Turkey is still more liberal and Westernized than the Shah's Persia ever was.

We don't have time to discuss "what is extreme, superficial, fundamental". The tone of your responses shows that you focus on own confirmation bias rather than open judgement of differences and their significance. There are many ways to sort Wikipedia facts. Some specific sorts would be optimal to see capably where the world is "stretching" now - but it is too costly for us to debate this fully academically. Nor we are qualified, or determined to have actual impact.

It is only since recently that I consider historical-social-religous-psychological backlashes against progress, enlightenments seriously. Here I have an occassion to share newly informed contemplations. But my time is limited, so I am not on a big educational mission.

To me, "political demand" versus "zealous supply" is a significant distinction. As for Sunni caliphate aspirations, I refer to this acclaimed Atlantic article for a start: "What ISIS Really Wants"

Ironically and in a few ways, this discussion exemplifies what is apparently wrong with progressive aspirations. We do not have all energy to really sell Rationalism to everyone. And our rigid criteria limits own understanding of other sentiments.

For what it's worth, I continue my IMHO sub-academic discussion of both differences and similarities on the subject of parallels to the caliphate, where I see a direct connection to the investiture conflict.

Unlike Islam or Confucianism, Christianity started out without a direct connection to state power, which it only gained in the 4th century when it was turned into the state religion of the Roman Empire. In the Roman Empire, and its descendant the Byzantine Empire, the Emperors developed an ideology of divine justification of power and exerted practical control over the church, which modern historians call Caesaropapism. But what is IMHO more interesting is what became of this tradition in the West.

When the Frank kings sought to re-establish the Roman Empire, this included the religious justification of power. For example, Charlemagne was quite brazen:

In any event, Charlemagne used these circumstances to claim that he was the renewer of the Roman Empire, which had apparently[citation needed] fallen into degradation under the Byzantines. In his official charters, Charles preferred the style Karolus serenissimus Augustus a Deo coronatus magnus pacificus imperator Romanum gubernans imperium[71] ("Charles, most serene Augustus crowned by God, the great, peaceful emperor ruling the Roman empire") to the more direct Imperator Romanorum ("Emperor of the Romans").

The claim of religious authority, of course, also translated into practical control of the Papacy. The investiture conflict was directly preceded by the church's rebellion against this:

The crisis began when a group within the church, members of the Gregorian Reform, decided to rebel against the rule of simony by forcefully taking the power of investiture from the ruling secular power, i.e. the Holy Roman Emperor and placing that power wholly within control of the church. The Gregorian reformers knew this would not be possible so long as the emperor maintained the ability to appoint the pope, so their first step was to forcibly gain the papacy from the control of the emperor. An opportunity came in 1056 when Henry IV became German king at six years of age. The reformers seized the opportunity to take the papacy by force while he was still a child and could not react. In 1059, a church council in Rome declared, with In Nomine Domini, that leaders of the nobility would have no part in the selection of popes and created the College of Cardinals as a body of electors made up entirely of church officials. Once Rome regained control of the election of the pope, it was ready to attack the practice of investiture and simony on a broad front.

In 1075, Pope Gregory VII composed the Dictatus Papae. One clause asserted that the deposal of an emperor was under the sole power of the pope.[5] It declared that the Roman church was founded by God alone - that the papal power (the auctoritas of Pope Gelasius) was the sole universal power; in particular, a council held in the Lateran Palace from 24 to 28 February the same year decreed that the pope alone could appoint or depose churchmen or move them from see to see.[6] By this time, Henry IV was no longer a child, and he continued to appoint his own bishops.[5] He reacted to this declaration by sending Gregory VII a letter in which he withdrew his imperial support of Gregory as pope in no uncertain terms: the letter was headed "Henry, king not through usurpation but through the holy ordination of God, to Hildebrand, at present not pope but false monk".[7] It called for the election of a new pope. His letter ends, "I, Henry, king by the grace of God, with all of my Bishops, say to you, come down, come down!", and is often quoted with "and to be damned throughout the ages." which is a later addition.[7][8]

Note how Henry IV claims to be king "through the holy ordination of God" (rather than the Pope). It wasn't until the height of the investiture conflict that the Frankish empire began to call itself Holy Roman Empire, though. (Its claim of supremacy becoming increasingly hollow, it existed until the early 18th century.)

When compared to the Sunni Caliphate, what stands out to me is not the position of the Emperor but the position of the Pope. AFAIK in Sunni Islam, you rarely find a top cleric with (at least symbolic) power comparable to that of the secular ruler (Muhammad ibn Abd al-Wahhab is the exception); and even in Shi's Islam or Orthodox Christianity, the religious authority of top clerics is usually limited to a state.

How could the Papacy not just endure but strengthen after repeated attempts by rulers (not just Holy Roman Emperors but French kings, too) to make it their tool? I think the reason is less religious than political. Already before the investiture conflict, requesting a crown from the Pope was a means for kings of newly established Christian kingdoms to protect their independence from the two Empires (Byzantine and Frakish). In the first round of the investiture conflict, the Emperor had to back down because his barons used the occasion to rebel against his authority. There was loss of central control in Sunni Islam, too, but instead of using an independent religious authority as catalyst, the renegades established rival caliphates.

The political evolution of Christianity is rich indeed, in a clear contrast to Islam's. Is this the difference between ongoing concurring successes and early traumas of Crusades, Mongols? Or does the desert environment lead to intellectual dessert, ha?

Henry IV presumed that he had not only the right but also the duty to poke his nose in the affairs of the church, Holland says. Gregory's victory intended to assure that the business of the church was of the church alone.

Paradoxically, the incident, known as the "Investiture Crisis," eventually led to the idea of separation of church and state.

Now I am reading "Desert Queen", a biography of Gertrude Bell. The Arab religious leader around WWI was Sharif Hussein. His sons led the Arab revolt, together with T. E. Lawrence. Hussein declared himself a caliph briefly in 1924, but was soon militarily eclipsed by ibn Saud.

The political evolution of Christianity is rich indeed, in a clear contrast to Islam's.

I don't see how that follows from what I wrote, at all. I wrote about the parallel evolution of the Sunni caliphate and the Holy Roman Empire ideas. The former is just as complex. It first moved from a notionally elected leader to a hereditary concept, then absorbed Persian imperial culture, then came rival caliphates, then appropriation by dynasties without connection to Muhammad. And that's just the Sunni idea of the Caliphate.

Further, given that we are discussing the time period before the Mongol invasion, when Christian Europe still had everything to learn from the Muslim world intellectually, your "intellectual desert" speculation is totally off.

Regarding the Tom Holland quote, "eventually led to the idea of" is a lot weaker than your "inauguration of". Perhaps it will prove useful if I go into more detail. The outcome of the investiture conflict didn't change the facts that bishops were also feudal lords, attended the imperial assembly (Reichstag), and 3 of the originally 7 electors choosing new Holy Roman Emperors were cardinals. Neither was there a change in the Empire (as well as kingdoms independent from it) giving assistance to the Church in its hunt for heretics, and referring to divine authority and the Bible in its laws. What did change was only that the authority to appoint the same bishops as feudal lords and as church leaders was separated (forcing the Empire and the Papacy into compromises). I think real separation means the removal of the Church from state institutions and religious references from law. (BTW, in some Catholic states, this gathered steam well after the start of Enlightement.)

"eventually led to the idea of" is a phrase of a reviewer. Tom Holland is very emphatic that the Canossa episode was a significant crossroad in European history. Islam may have been similarly dynamic at that time, but the dispute between the Henries and the Popes was a special development that defined European norms and enabled a more dynamic trajectory. Sunni complexities remained chronological facts somehow.

Our general discussion is not just about before the Mongol invasion (especially if you still pivot on the real separation). It is surely an open question how Christianity would have coped with the Mongols if they would have seen Europe worthwhile to conquer. But the Mongol impact on the Middle East soil and ideology was pretty arresting.

I have The Collected Letters of Gertrude Bell along with The Memoirs of Aga Khan in my library. I found them in a group of books on sale to the public from Cal State LA. Primary source material! I was appalled and snapped them up. Possibly a case of the university no longer having a middle east specialist on its faculty. I haven't taken the time to read either yet.

As the Dutch said while fighting the Spanish: "It is not necessary to have hope in order to persevere." (But it helps!)

Cal State Northridge it was. CSULA has an excellent middle east historian, but he wouldn't get into issues involving the Saudi monarchy. Told me about giving one talk and, afterwards, having an agent of the Saudi government come up to him and tell him: "You got things right THIS time." He has extended family in Alexandria.

As the Dutch said while fighting the Spanish: "It is not necessary to have hope in order to persevere." (But it helps!)